G21 G90
G0 X0 Y0 Z0
F100
O<move_plus> call [4] [6]
G1 X20
M30
O<move_plus> sub
#<sum> = [#1 + #2]
G1 X#<sum>
G1 Y#2
O<move_plus> return
G1 X99
O<move_plus> endsub